Yes, a good night’s sleep. Maybe. The Harvard School of Public Health reports that research conducted there and at the University of Iceland in Reykjavik suggests that men who sleep longer and with fewer interruptions have increased levels of the sleep hormone melatonin in their urine and are 75 percent less likely to develop advanced prostate cancer than those with less melatonin. Melatonin, since you asked, is produced in the brain in response to darkness and is influenced by the amount and quality of sleep. Men who wake multiple times during the night or who work nightshifts may be more at risk for disrupting production of the hormone. Read more from the Harvard School of Public Health News.